Wind Tolerance
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An engineering firm can give you that answer... but without knowing what you are hanging on it there is no real way to know.
In general, you should always weight the bottom of any stand, so "without the sand bags" should never be an option. Truss by itself has a very small cross section that is not that susceptible to wind. Now, signs, lights, disco balls, speakers, and all that fun stuff do have a large footprint and can cause more resistance.
If you need to find this answer, draw up what you are doing and give it to an engineering firm to do an analysis on. No one here is just going to throw out a number, there are way to many variables at work and no one is going to put their name on it.
In general, you should always weight the bottom of any stand, so "without the sand bags" should never be an option. Truss by itself has a very small cross section that is not that susceptible to wind. Now, signs, lights, disco balls, speakers, and all that fun stuff do have a large footprint and can cause more resistance.
If you need to find this answer, draw up what you are doing and give it to an engineering firm to do an analysis on. No one here is just going to throw out a number, there are way to many variables at work and no one is going to put their name on it.
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JD
Well-Known Member
Much of this type of equipment is designed for indoor use (weddings, etc.) and not really designed to handle diagonal stress. Even indoors there can be problems if you are using something other than lightweight par cans. Remember, "movers" move, and in the process produce momentive loads.
As a matter of liability, we don't really discuss rigging on this form. The greatest cost is not that of the equipment, but what happens should it fail/fall and injure someone. As such, you should at least contact the manufacturer, or as Footer has suggested, talk to an engineer who has experience in this area.
Wind can be your biggest enemy: http://www.controlbooth.com/forums/news/25471-stage-rigging-collapses-indiana-state-fair.html
As a matter of liability, we don't really discuss rigging on this form. The greatest cost is not that of the equipment, but what happens should it fail/fall and injure someone. As such, you should at least contact the manufacturer, or as Footer has suggested, talk to an engineer who has experience in this area.
Wind can be your biggest enemy: http://www.controlbooth.com/forums/news/25471-stage-rigging-collapses-indiana-state-fair.html
MarfaLights
Member
I think the proper answer is none! How about this. Mount your rig on a flat bed trailer and then drive down a closed road in calm conditions. Note the speed when your rig falls over. But seriously, these things need to be designed to handle the highest possible gusts. Avoiding windy days is not the same thing.
I do construction full-time and lighting part-time. I'm always thinking wind blowing things around... Wind plays tricks around buildings. And stages.
I do construction full-time and lighting part-time. I'm always thinking wind blowing things around... Wind plays tricks around buildings. And stages.
Les
Well-Known Member
Are you talking about one of these?
You did leave out a very crucial element -- how high will the stands be extended and what kind of weight are you putting on there? I'm not sure how you expect to get a reliable answer without providing that information.
That said, with a load capacity of only 200 lbs and a very conservative footprint, I'm going to have to agree that these stands aren't designed to be stable in any wind conditions.
You did leave out a very crucial element -- how high will the stands be extended and what kind of weight are you putting on there? I'm not sure how you expect to get a reliable answer without providing that information.
That said, with a load capacity of only 200 lbs and a very conservative footprint, I'm going to have to agree that these stands aren't designed to be stable in any wind conditions.
MPowers
Well-Known Member
Our standard base charge for a wind analysis calculation for an outdoor venue starts at $1500 and depending on size and type of the structure, roof (or not), vertical scenic panels, and number of components, etc. goes up from there.
Also, there is no standard calculation. While a free standing figure can be calculated (hypothetical condition standing in the middle of an infinate flat plain with a steady wind of a given magnitude)(which actually sounds like what you are hoping for), different locations will have different figures. For example, when located adjacent to a lake or river, the wind factor goes up. The orientation of the structure on site, in relation to prevailing winds, other lagre structures or geographic features can also affect the calculations. When doing calculations for a speciffic site, there actually two sets of calculations. The first is free standing figure for the structure. Then for the probable worst condition wind loads from the site. The structure then must be guyed, braced weighted etc. for that wind load as a minimum, plus an acceptable safety factor. Then you create a safety plan. At what wind speeds do you lower the roof, Lower scenic units or vertical pannels or speaker clusters etc.? When do you clear the stage or areas with overhead structure? When do you evacuate? Who makes the call? All of these things and more go into a wind load calculation.
I know this may seem extreme for a 10' ladder truss across two 10' high stands, but those are the factors that must be considered. If your structure is like the one pictured, with tripod style legs, sand bags would be of very little help, where would you place them? Guy wires to ballasts or HD stakes would be a better choice.
